Heterogeneous Yarns For Surgical Articles

ABSTRACT

Heterogeneous yarns containing strands of dissimilar materials are useful in forming surgical device.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of, and claims the benefit ofand priority to, co-pending U.S. patent application Ser. No. 12/504,954filed on Jul. 17, 2009, which is a continuation-in-part of, and claimsthe benefit of and priority to, U.S. patent application Ser. No.10/917,183 filed on Aug. 12, 2004, now abandoned, which claims priorityto and the benefit of U.S. Provisional Application No. 60/494,993 filedon Aug. 14, 2003, the entire disclosures of each of which are herebyincorporated by reference in their entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to yarns made of dissimilar materials.Filaments of at least two dissimilar materials are combined to form ayarn which, in turn, can be braided, woven, etc. to form a devicesuitable for surgical use.

2. Background of Related Art

Sutures intended for the repair of body tissues must meet certainrequirements; they must be substantially non-toxic, capable of beingreadily sterilized, they must have good tensile strength and haveacceptable knot-tying and knot-holding characteristics and, if thesutures are of the bio-absorbable variety, the bio-absorption of thesuture must be closely controlled.

Sutures have been constructed from a wide variety of materials includingsurgical gut, silk, cotton, polyolefins such as polypropylene,polyamides, polyesters such as polyethylene terephthalate, polyglycolicacid, glycolide-lactide copolymer, etc. Sutures have been constructedfrom these materials in a monofilament form and as braided structures.For example, sutures manufactured from silk, polyamide, polyester andbio-absorbable glycolide-lactide copolymer are typically provided asmulti-filament braids.

Filaments have also been utilized to form other mutli-filament surgicalor medical devices, such as braided tapes, gauze, wound dressings,hernial repair meshes, vascular grafts (e.g. fabrics and/or tubes)anastomosis rings, prosthetic ligaments and tendons, growth matrices,drug delivery devices and other implantable medical devices.Multi-filaments braids typically provide the advantages of enhancedpliability, and tensile strength as compared to monofilamentconstructions, and where utilized as sutures, posses enhanced knotsecurity. The enhanced pliability of a multi-filament braid is caused bya lower resistance to bending of a strand of very fine filaments asopposed to one large diameter monofilament. The individual filamentsmust be able to bend unencumbered or unrestricted by their neighboringfilaments. Any mechanism which reduces this individual fiber mobility,such as simple fiber-fiber friction, a coating which penetrates into thebraid interstices, or a melted polymer matrix which adheres fiberstogether, could adversely affect braid pliability. It would beadvantageous to combine dissimilar materials or fibers to form filamentstrands to enhance pliability and strength.

SUMMARY

The present disclosure relates to biocompatible composite surgicaldevices made from heterogeneous yarns. The yarns contain multiplestrands of a polyester material and multiple strands of a polyolefinmaterial. The strands are combined in substantially parallel lengthswith respect to each other to form the heterogeneous yarn. The yarns canthen be braided, knitted or woven to form medical/surgical devices,including sutures.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross sectional view of a heterogeneous yarn of polyesterand polyolefin strands;

FIG. 2 shows a needle-suture combination in accordance with the presentdisclosure;

FIG. 3 is a perspective view of a portion of a split human sternumillustrating one application of the present invention for retaining thesplit portions together to promote healing;

FIG. 4 is an enlarged view of the suture product shown in FIG. 3illustrating one embodiment wherein the elongated product is a flatbraided member and contains at least eight reinforcing filamentsextending along the length;

FIG. 5 is a view of an alternative embodiment of the suture repairproduct wherein the elongated member is a spiroid braided member havinga generally circular cross-section containing at least one elongatedreinforcing member; and

FIG. 6 is a view of another alternative embodiment of the suture repairproduct wherein the elongated product is a hollow braided member havinga generally circular cross-section and contains at least one elongatedreinforcing member extending centrally thereof along the length.

DETAILED DESCRIPTION

The present disclosure relates to heterogeneous yarns, which can be usedin the fabrication in whole or in part of a variety of textile surgicaldevices, including, for example, sutures, braided tapes, gauze, wounddressings, hernial repair meshes, vascular grafts (e.g. fabrics and/ortubes) anastomosis rings, prosthetic ligaments and tendons, growthmatrices, drug delivery devices and other implantable medical devices.An implantable medical device is defined as any device which can beimplanted in an animal for medical purposes. The yarns can be braided,knitted or woven to form the devices.

In accordance with the present disclosure, at least two different kindsof fibers or strands are placed in intimate contact to form aheterogeneous yarn. More particularly, the heterogeneous yarns containstrands made from a polyester and strands made from a polyolefin.Multiple strands of polyester and polyolefin are combined to form asingle yarn. Multiple heterogeneous yarns thus obtained are thenbraided, knitted, or woven to form a multi-filament surgical/medicaldevice, such as, for example, a multi-filament surgical suture.

In particularly useful embodiments, the polyester strands are made ofpolyethylene terephthalate. Polyethylene terephthalate is athermoplastic polyester formed by esterification from ethylene glycoland terephthalic acid. Its advantageous properties include high tensilestrength, high resistance to stretching under both wet and dryconditions, and good resistance to degradation by chemical bleaches andto abrasion. Polyethylene terephthalate is commercially available fromDuPont Corporation, Wilmington, Del., under the trademark DACRON®.

The polyolefin strands are preferably made from a polyethylene. Inparticularly useful embodiments, the polyethylene is an ultra highmolecular weight polyethylene. Ultra high molecular weight (“UHMW”)polyethylene is a linear polymer with an average molecular weightgreater than about 400,000, typically in the range of about 500,000 toabout 6,000,000. UHMW polyethylene has a high tenacity and lowelongation rate to provide articles with greatly increased strength anddecreased elongation.

UHMW polyethylene typically exhibits a very substantial degree ofcrystalline orientation (95-99%) and crystalline content (60-85%). Thesignificant strength and stability of UHMW polyethylene is normallycaused by the high degree of molecular orientation. As a result, thefibers exhibit strengths from about 375 kpsi (thousands of pounds persquare inch) to about 560 kpsi, and tensile moduli of about 15 msi(millions of pounds per square inch) to about 30 msi. Ultra highmolecular weight polyethylene is commercially available under thetrademark SPECTRA®. from Allied-Signal Technologies, Petersburg, Va.,and under the trademark DYNEEMA® from DSM High Performance Fibers, JHHeerlen, The Netherlands.

The yarn may optionally contain strands of other materials. Materialsused to construct these optional strands can include a wide variety ofnatural and synthetic fibrous materials such as any of those previouslyknown for the construction of sutures. Such materials includenon-absorbable as well as partially and fully bio-absorbable (i.e.,resorbable) natural and synthetic fiber-forming polymers, includingthermoplastics. Suitable non-absorbable materials can include, forexample, polyamides, polyesters such as polyethylene terephthalate,polyacrylonitrile, polyolefins such as polyethylene and polypropylene,silk, cotton, linen, etc. Carbon fibers, steel fibers and otherbiologically acceptable inorganic fibrous materials can also beemployed. Bio-absorbable resins can include those derived from glycolicacid, glycolide, lactic acid, lactide, dioxanone, epsilon-caprolactone,trimethylene carbonate, etc., and various combinations of these andrelated monomers.

The strands which form the yarns can be made using any known technique,such as, for example, extrusion, molding and/or solvent casting. In apreferred embodiment, the strands can be extruded through an extruderunit of a conventional type, such as those disclosed in U.S. Pat. Nos.6,063,105; 6,203,564; and 6,235,869, the contents of each of which areincorporated by reference herein. The strands of dissimilar materialscan be extruded separately and subsequently brought together into agroup to form a yarn, or the strands can be extruded in a side-by-sidefashion and collected together to immediately form a yarn. The number ofstrands used per yarn will depend on a number of factors including thedesired final size of the yarn and the ultimate multi-filament articlebeing produced. For example, with respect to sutures, size isestablished according to United States Pharmacopoceia (“USP”) standards.However, each yarn can contain at least ten strands, and often more, ofat least two differing material types. The strands run parallel to eachother along the length of the yarn. Although twisting the strands toform a twisted yarn is also contemplated.

Turning now to FIG. 1, heterogeneous yarn 10 of the present disclosureis shown. Yarn 10 may be formed, in embodiments extruded, to anysuitable length. More particularly, the extruded length of the yarn 10may be determined by the intent of use of the yarn 10. For example, inthe instance where the intended use of the yarn 10 is for themanufacture of a suture 101, the yarn 10 includes a length that is atleast equal to the length of the suture (see FIG, 2, for example). Inembodiments, yarn 10 may include lengths that are from about 5 inches toabout 144 inches. For illustrative purposes, a segment of a yarn 10 isdepicted in FIG. 1 and includes a plurality of polyolefin strands 12(such as, UHMW polyethylene) and polyester strands 14 (such as DACRON®).While only a segment of yarn 10 is depicted in FIG. 1, it is to beunderstood that, in embodiments, the parallel orientation of strands 12and 14 may be maintained along the entire length of yarn 10 (not shown).In other words, the plurality of strands 12 and 14 run parallel to botheach other and the longitudinal axis of yarn 10, along the length ofyarn 10.

As noted above, yarn 10 may be formed by one or more known extrusionprocesses. After the strands 12 and 14 have been extruded andsubsequently brought together and/or collected, each of the strands 12and 14 are arranged and maintained so that they are in intimate contactwith each other in a parallel relation relative to one another. Thisparallel configuration of strands 12 and 14 may increase the structuralintegrity of the yarn 10.

The strands 12 and 14 may be maintained in this parallel relation by anysuitable methods and/or processes. For example, in an embodiment, thestrands 12 and 14 may be temporarily positioned within a holdingreceptacle, such as, for example, a removable forming sheath (notshown). The forming sheath may be configured to maintain the strands 12and 14 in a parallel configuration during the formation of the yarn 10.

In embodiments, after the strands 12 and 14 have been positioned withinthe forming sheath, the strands 12 and 14 may be subsequently bonded toeach other by any means within the purview of those skilled in the art.Such means may include, for example, the application of heat, the use ofbinding agents, the use of coatings, combinations thereof, and the like.In embodiments, instead of a forming sheath, a permanent sheath may beapplied to the external surface of yarn 10, thereby assisting inmaintaining the parallel orientation of strands 12 and 14.

A sheath which is applied to the strands 12 and 14 and left thereon tomaintain their parallel orientation may be formed of any materials usedto form strands 12 and/or 14, as well as any other component utilized toform a suture of the present disclosure.

Depending upon the materials utilized to form the strands, inembodiments, suitable heating to fuse the strands together may includeheating to from about 70° C. to about 160° C., in embodiments from about100° C. to about 140° C.

The heating may be dependent upon the glass transition temperature ofthe materials utilized to form the strands. Moreover, in embodiments, itmay be desirable to heat the strands under tension, to maintain theparallel orientation of the strands.

Suitable binding agents are within the purview of those skilled in theart and include suitable biocompatible adhesives, thermoplastic resins,waxes, combinations thereof, and the like. In embodiments, a pluralityof interstices “I” may be formed between the plurality of strands 12 and14. The interstices “I” run parallel to each other and the strands 12and 14 along the length of the yarn 10. In embodiments, the plurality ofinterstices may be configured to provide an area for receiving thebinding agent “A”. The binding agent “A” may be applied along the entirelength of the yarn, or in discrete locations along the length of theyarn. In embodiments it may prove useful to apply the binding agent maybe deposited at specific locations or nodes “n” along the length of theyarn, see FIG. 1. The plurality of nodes “n” and/or forming sheath maybe configured to receive the binding agent at correspondingpredetermined locations along the length of the yarn 10. The pluralityof nodes “n” may be configured to maintain the strands 12 and 14 in afixed parallel relation relative to one another.

Thus, in embodiments, a method for forming a yarn of the presentdisclosure may include positioning a plurality of strands inside-by-side fashion such that the plurality of strands are maintainedin a parallel relation relative to one another, applying a binding agentto the plurality of heterogeneous strands, and setting the binding agentto assist in maintaining the strands in their parallel configuration.

Any biocompatible adhesive may be utilized. In embodiments, suitableadhesive materials include synthetic absorbable and non-absorbablemonomers and oligomers including those synthesized from materials suchas lactic acid, glycolic acid, caprolactone, dioxanone, polyethyleneglycol (PEG), polypropylene glycol, isocyanates, copolymers thereof,combinations thereof, and the like. Adhesive materials may be combinedwith solvents for their application, including polar and non-polarsolvents. Suitable solvents include alcohols, e.g., methanol, ethanol,propanol, chlorinated hydrocarbons (such as methylene chloride,chloroform, 1,2-dichloro-ethane), and aliphatic hydrocarbons such ashexane, heptene, ethyl acetate.

The specific manner in which the binding agent may be applied to theyarn 10 will depend on the contemplated uses of the suture. After thebinding agent is applied to the strands 12 and 14, strands 12 and 14and/or the binding agent may be set using known curing methods orprocesses (e.g., ultra-violet curing) or other suitable methods orprocesses not described herein.

In embodiments, the strands 12 and 14 and/or the binding agent may besimultaneously subjected to an ultra-violet curing process. Followingthe ultra-violet curing process, the forming sheath may be subsequentlyremoved, producing a yarn 10 that includes the strands 12 and 14 in afixed parallel configuration.

In embodiments, after the strands 12 and 14 have been set or formed inthe fixed parallel configuration, the yarn 10 including the strands 12and 14 may be treated with a suitable coating (not shown). Inembodiments, the coating may be employed to facilitate in maintainingthe strands 12 and 14 in a parallel configuration. Any biocompatiblecoating may be applied thereto, including those disclosed in U.S. PatentApplication Publication Nos. 2008/0268243, 2007/0207189, 2007/0010856,2006/0188545, 2004/0153125, and 2004/0147629, and U.S. Pat. Nos.6,878,757, 6,136,018, 6,007,565, and 5,716,376, the entire disclosuresof each of which are incorporated by reference herein.

A coating and/or sheath may be applied in discrete locations or, inembodiments, may be applied along the longitudinal distance of thesuture. Where applied in discrete locations, the locations may beintermittent and/or discrete, or may be along one or more partiallengths of continuous and/or increasing and/or decreasing change inlength along the suture.

Once formed, a plurality of the heterogeneous yarns 10 can then bebraided, knitted, or woven together. The braiding can be done by anymethod known to those skilled in the art. For example, braidconstructions for sutures and other medical devices are described inU.S. Pat. Nos. 5,019,093; 5,059,213; 5,133,738; 5,181,923; 5,226,912;5,261,886; 5,306,289; 5,318,575; 5,370,031; 5,383,387; 5,662,682;5,667,528; 6,203,564; the contents of each of which are incorporated byreference herein. Once the suture is constructed, it is preferablysterilized, by any means known to those skilled in the art.

Braided surgical devices made using heterogeneous yarns prepared inaccordance with the disclosure can optionally be coated with one or morecoating compositions to improve functional properties of the device. Forexample, a coating can be applied to improve surface lubricity and knottie-down behavior. Suitable coating compositions include but are notlimited to those disclosed in U.S. Pat. Nos. 3,867,190; 3,942,532;4,047,533; 4,452,973; 4,624,256; 4,649,920; 4,716,203; 4,826,945; and5,569,302, the disclosures of which are incorporated by referenceherein. The coating can be applied using any known technique such as,for example coating, dipping, spraying or other appropriate techniques.

The amount of coating composition applied to the device will varydepending upon the specific construction of the device, its size and theexact material of its construction. In general, the coating compositionwill constitute from about 0.5 to about 4.0 percent by weight of thecoated device or higher with a preferred range from about 1.0 percent toabout 3.0 percent.

A surgical device prepared from the presently described heterogeneousyarns may also be impregnated with one or more medico-surgically usefulsubstances, e.g., those which accelerate or beneficially modify thehealing process when the suture is applied to a wound or surgical site.The medically useful or therapeutic agents can include varying amountsof one or more optional ingredients, such as, for example, bioactivesubstances such as biocidal agents, antibiotics, antimicrobials,medicants, growth factors, anti-clotting agents, analgesic, anesthetics,anti-inflammatory, etc., and the like. Medicants are defined assubstances which are beneficial to the animal and tend to promote thehealing process. For example, a braided suture can be provided with atherapeutic agent which will be deposited at the sutured site. Thetherapeutic agent can be chosen for its antimicrobial properties,capability for promoting wound repair and/or tissue growth, or forspecific indications such as thrombosis. Antimicrobial agents such asbroad spectrum antibiotics (gentamicin sulphate, erythromycin orderivatized glycopeptides) which are slowly released into the tissue canbe applied in this manner to aid in combating clinical and sub-clinicalinfections in a surgical or trauma wound site. To promote wound repairand/or tissue growth, one or more biologically active materials known toachieve either or both of these objectives can also be applied to thebraided suture. Such materials include any of several human Growthfactors (HGFs), magainin, tissue or kidney plasminogen activator tocause thrombosis, superoxide dismutase to scavenge tissue-damaging freeradicals, tumor necrosis factor for cancer therapy, colony stimulatingfactor, interferon, interleukin-2 or other lymphokines to enhance theimmune system, and so forth.

The braided device prepared from heterogeneous yarns in accordance withthis disclosure can also include, for example, biologically acceptableplasticizers, antioxidants, and colorants, which can be impregnated intothe heterogeneous yarns of the device.

In addition, the yarn and/or product may be plasma treated dependingupon the particular needs or intended application so as to reduce theperceived “slipperiness” of the product as desired.

The braided suture 101 prepared in accordance with this disclosure canhave a needle 102 attached thereto as shown in FIG. 2, to provide aneedle suture combination 100. In order to facilitate needle attachment,conventional tipping agents can be applied to the braid. Two tipped endsof the suture may be desirable for attaching a needle to each end of thesuture to provide a so-called double armed suture. The needle attachmentcan be made by any conventional method such as crimping, swaging, etc.,including those described in U.S. Pat. Nos. 5,133,738; 5,226,912; and5,569,302, the disclosures of which are incorporated by referenceherein.

As noted above the heterogeneous yarns of the present disclosure canalso be utilized to form other surgical or medical articles, including,braided tapes, gauze, wound dressings, hernial repair meshes, vasculargrafts (e.g. fabrics and/or tubes) anastomosis rings, prostheticligaments and tendons, growth matrices, drug delivery devices and otherimplantable medical devices.

Referring initially to FIG. 3 there is illustrated a sternum closureribbon 110 constructed according to the present invention and positionedto retain portions 112, 114 of a human sternum 116 together. The band110 is a braided product made from the heterogeneous yarns describedherein. In FIG. 4, the band 110 shown in FIG. 3 is shown in greaterdetail as an elongated flat braided textile product prepared asdescribed in U.S. Pat. No. 5,318,575, the disclosure of which isincorporated herein by reference, with the exception that heterogeneousyarns in accordance with the present disclosure are used in theconstruction.

Accordingly, it is possible in one application to position thereinforced structure 110 about the split portions 112, 114 of the humansternum 116 as shown in FIG. 3 whereby substantial force may be appliedto the band by tying the band either by a knot 122 shown in FIG. 3, orby other techniques whereby significant force may be applied andretained to promote natural healing of the sternum portions 112, 114,e.g. mechanical connecting devices such as buckles, etc. See, forexample, U.S. Pat. No. 4,813,416.

In FIG. 5, there is an alternative elongated embodiment of spiroidbraided construction of generally circular cross-section and comprisedof heterogeneous yarns 126 combined to form a braided rope-likeconstruction of generally circular cross-sectional configuration. Braidconstructions having a circular cross-section are described in U.S. Pat.Nos. 3,565,077 and 5,019,093. In FIG. 6 there is shown a hollow braidconstruction 128 having a sheath constructed of heterogeneous yarns 130and having a core 132.

Surgical devices prepared from heterogeneous yarns in accordance withthis disclosure can be packaged and sterilized in any conventionalmanner known to those skilled in the art.

It will be understood that various modifications may be made to theembodiments disclosed herein. For example, in any of the braidedproducts described herein one or more of the yarns may be heterogeneousyarns in accordance with this disclosure while the remaining portionsare made of absorbable or non-absorbable fibers or filaments. As oneillustrative example, for braided products containing a core/sheathstructure, the core may be a heterogeneous yarns in accordance with thisdisclosure while the sheath yarns can be made form other biocompatiblefibers, including, but not necessarily, bioabsorbable fibers. Thereforethe above description should not be construed as limiting, but merely asexemplications of preferred embodiments. Those skilled in the art willenvision other modifications within the scope and spirit of the claimsappended hereto.

1. A method of manufacturing a yarn for use with a surgical devicecomprising: positioning a plurality of heterogeneous strands inside-by-side fashion such that the plurality of heterogeneous strandsare maintained in a parallel relation to one another; applying a bindingagent to the plurality of heterogeneous strands; and setting the bindingagent.
 2. A method according to claim 1, further comprising forming theheterogeneous strands via an extrusion process.
 3. A method according toclaim 2, wherein the plurality of heterogeneous strands are extruded toa length from about 5 inches to about 144 inches.
 4. A method accordingto claim 1, wherein positioning the plurality of heterogeneous strandsoccurs within a holding receptacle configured to maintain the pluralityof heterogeneous strands in the parallel relation to one another.
 5. Amethod according to claim 4, wherein the holding receptacle is a formingsheath.
 6. A method according to claim 4, wherein the holding receptacleis a permanent sheath that is applied to a surface of the plurality ofheterogeneous strands.
 7. A method according to claim 4, wherein theholding receptacle is made from the same material as the plurality ofheterogeneous strands.
 8. A method according to claim 1, wherein settingthe binding agent occurs by heating the binding agent.
 9. A methodaccording to claim 8, wherein heating the binding agent occurs at atemperature from about 70° C. to about 160° C.
 10. A method according toclaim 8, wherein heating the binding agent occurs at a temperature fromabout 100° C. to about 140° C.
 11. A method according to claim 8,wherein heating the binding agent further comprises tensioning theplurality of heterogeneous strands to facilitate maintaining theparallel relation of the plurality of heterogeneous strands with respectto one another.
 12. A method according to claim 1, wherein the bindingagent is applied along the entire length of the plurality ofheterogeneous strands.
 13. A method according to claim 1, wherein thebinding agent is applied along discrete locations along the length ofthe plurality of heterogeneous strands.
 14. A method according to claim1, wherein the binding agent is selected from the group consisting ofbiocompatible adhesives, thermoplastic resins, waxes, and combinationsthereof.
 15. A method according to claim 14, wherein the biocompatibleadhesives are selected from the group consisting of synthetic absorbableand non-absorbable monomers and oligomers.
 16. A method according toclaim 15, wherein the synthetic absorbable and non-absorbable monomersand oligomers are selected from the group consisting of lactic acid,glycolic acid, caprolactone, dioxanone, polyethylene glycol (PEG),polypropylene glycol, isocyanates, copolymers thereof, and combinationsthereof.
 17. A method according to claim 1, wherein positioning theplurality of heterogeneous strands in side-by-side fashion forms acorresponding plurality of interstices between the plurality ofheterogeneous strands.
 18. A method according to claim 17, wherein theplurality of interstices are configured to provide an area for receivingthe binding agent therein.